1. Field of the Invention
This invention relates to and has among its objects the provision of a novel process and apparatus for shrinkproofing proteinous animal fibers, e.g., wool, mohair, and the like, or blends of these fibers with non-proteinous animal fibers such as cotton, polyester, acrylic, etc. Further objects of the invention will be evident from the following description wherein parts and percentages are by weight unless otherwise specified.
2. Description of the Prior Art
As a general proposition, the treatment of wool with ozone has been described heretofore and has been suggested as a means of improving the shrinkage properties of the textile. Various investigators have explored the situation and have advocated different techniques for accomplishing their desired ends. A typical procedure is that described in British Pat. No. 242,027, Nov. 5, 1925. In this process wool is soaked in 5% ammonia solution for a few minutes, hydro-extracted (centrifuged) to remove excess liquid, and then placed while damp in a chamber werein it is exposed to air containing ozone in a concentration of about one part per 1000. The process is exceedingly slow as evidenced by the fact that the patentees suggest removing samples of wool "at intervals of a few hours" to test them for acidity. (If acid, the wool is again soaked in ammonia solution prior to further ozone treatment.) The procedure of the British patent, termed the "Zair" process, was further investigated by Brown (Journal of the Society of Dyers and Colourists, Vol. 44, pp. 230-233, 1928) who illustrates the long duration of the process, i.e., 5 to 20 hours. In addition to requiring long processing times, the various prior procedures have involved such disadvantages as erratic and non-uniform results, decrease in abrasion resistance of the treated wool, and even loss of material during processing by dissolving of a portion of the fibers. As a net result, the ozone treatment of wool has not met with commercial acceptance.
More recently, the present inventor, Walter J. Thorsen, has shown in U.S. Pat. No. 3,149,906 ('906) that much faster shrinkproofing of wool is obtained where a stream of ozone and steam is blown through the textile under treatment. For example, it is shown in this patent that wool can be rendered shrinkproof in a processing time of 1 to 10 minutes. The steam-ozone mixture has an ozone content of about 10-50 milligrams/liter (mg/l). The temperature at which the patented process is carried out is about 60.degree.-95.degree. C. Generally, the ozone is produced in a conventional device wherein oxygen (or air) is passed through an electrical system involving a high-voltage silent discharge. The effluent gas from this device contains, for example, about from 10 to 100 mg/l of ozone, depending on the circuit adjustments of the device. The portion of this gas stream which is not ozone is, of course, oxygen (or air). This gas stream is mixed with a stream of steam produced by a conventional steam generator.
The '906 process is disadvantageous for the reason that machinery for conducting the process does not exist. Thus, the fiber processor necessarily would be required to expend a considerable amount of money to initiate the above invention. Further disadvantages are that ozone utilization is inefficient and shrinkproofing of sliver is impossible.
In U.S. Pat. No. 3,404,942 ('942) another method of shrinkproofing wool with ozone is disclosed. Heat is applied to one side of a proteinaceous fabric at a temperature in the range of 80.degree.-170.degree. C. Concomitantly, a gas stream containing ozone is passed over the opposite side of the fabric. The path of the ozone gas stream is confined adjacent and parallel to this side.
The '942 method requires a preliminary prewetting step (dip and pad stage). A further disadvantage is that during treatment dry ozone-laden air (or oxygen) passed over the dampened fabric causes a drying of this material. Extended treatment times result in a completely dried fabric and the reaction terminates, resulting in a waste of energy and time.